By Gene Cherry
HATTERAS ISLAND, North Carolina (Reuters) - Hurricane Earl strengthened on Wednesday, churning up dangerous swells, forcing evacuations on some of North Carolina's barrier islands and prompting storm alerts along much of the U.S. East Coast.
Watches and warnings were posted along the Atlantic coast for most of North Carolina, Virginia, Maryland, Delaware, New Jersey, New York, Connecticut, Rhode Island and part of Massachusetts, alerting residents that hurricane and tropical storm conditions were possible within 36 to 48 hours.
Earl had sustained winds of 135 mph as it barreled across the Atlantic, making it a powerful and dangerous Category 4 storm on the five-step Saffir-Simpson scale of intensity, the U.S. National Hurricane Center said.
While a direct U.S. landfall was not forecast, Earl was on track to deliver a sidelong blow to the North Carolina coast ahead of the Labor Day holiday weekend marking the end of the summer vacation season.
The hurricane's center is seen passing within 100 miles of the state's Outer Banks barrier islands late on Thursday or early on Friday. The islands jut out into the Atlantic and are frequently smacked by hurricanes and storms.
Forecasters said a low-pressure trough moving out of the southwest over the United States would push Earl to the northeast on Thursday, keeping it off the U.S. Coast. But they warned that any westward deviation from the forecast track could bring the core of the storm over the coast.
"If the turns occur a little bit later than we're forecasting it could bring more of a threat at that time to extreme eastern Long Island or southeastern New England," said Hurricane Center Director Bill Read.
No storm has threatened such a broad swath of the U.S. shoreline -- the densely populated coast from North Carolina to New England -- since Hurricane Bob in 1991, said hurricane center spokesman Dennis Feltgen.
Large swells roiled the coastline, and experts warned Earl would bring dangerously high seas. "We could potentially see (storm) surge over 12 feet in many areas, and that in fact would cause substantial property damage and property loss," said Howard Botts, a geologist with Corelogic who has close ties to the insurance industry.
EVACUATIONS ORDERED
Earl was a large storm with hurricane-force winds extending 90 miles from the center and tropical storm-force winds extending out 200 miles.
At 8 p.m. (2400 GMT), it was moving northwest through the Atlantic about 565 miles south-southeast of Cape Hatteras, North Carolina.
Energy companies expected Earl to miss key refineries in New Jersey and Pennsylvania, while nuclear plant operators in North Carolina and Virginia said they did not expect winds severe enough to force shutdowns.
North Carolina Governor Beverly Perdue declared a state of emergency, a move that eased transport restrictions and allowed speedier delivery of essential fuel and gasoline supplies.
North Carolina's Dare County ordered a mandatory evacuation of Hatteras Island, a picturesque vacation spot that draws large numbers of tourists each year. Officials said high waves could wash over the coastal highway, stranding those who stay behind.
Vacationers and residents jammed ferries bound for the mainland after evacuations were ordered on Ocracoke Island.
On Hatteras Island, visitor John Gusciora of Leesburg, Virginia, was reluctant to leave the village of Salvo, where he had rented a cottage with three families. The weather was sunny on Wednesday, with little or no breeze.
"It's disappointing. We've been coming down here for years and this is the best weather we've had until today. Now we have to try to pack up our bags and beat the rush off the island," Gusciora said. "It's sad to go, but it's better to be safe."
It was too early to predict how close the hurricane would come to New York City when it churns offshore east of the city over the weekend, but emergency officials urged local authorities and residents to stay alert.
INSURED LOSSES IN CARIBBEAN
Earl caused $50 million to $150 million in insured losses in the Virgin Islands, St. Maarten, St. Martin and Puerto Rico when it blew through the northeast Caribbean earlier this week, risk modeling company AIR Worldwide said.
Behind Earl, Tropical Storm Fiona was moving northwest over the open Atlantic, about 140 miles north of the Caribbean island of Anguilla on Wednesday, with winds up to 60 mph.
Fiona was expected to curve northeast in the Atlantic and keep far away from the U.S. coast while remaining a tropical storm at its peak intensity.
Tropical Storm Gaston formed in the Atlantic 895 miles west-southwest of the Cape Verde Islands and was expected to strengthen into a hurricane during the weekend. It was forecast to move west toward the northeast Caribbean islands.
(Additional reporting by Tom Brown and Pascal Fletcher in Miami, and Eileen Moustakis in New York; writing by Jane Sutton; editing by Pascal Fletcher and Mohammad Zargham)
